As a conventional discharge lamp ballast apparatus with a fault detecting function, there is one that has a section for detecting a power supply voltage and a section for detecting the voltage and current of a discharge lamp; detects a plurality of types of faults according to the discharge lamp voltage, the discharge lamp current and the power supply voltage; stores the number of occurrences of the faults and inhibits lighting the discharge lamp when the number of occurrences of the faults reaches a certain number of times; and enables a worker to check on a display the number of occurrences of the faults stored, thereby making it possible for the worker to check the presence or absence of the faults and their types easily (see Patent Document 1, for example).
In addition, as a conventional discharge lamp ballast apparatus with a function of detecting the life of a discharge lamp, there is one that has an integrating section for counting the cumulative lighting time of the discharge lamp and the number of times of lighting; and has a function of diagnosing that the life span of the discharge lamp exceeds when the cumulative lighting time goes beyond a prescribed CD value, and a function of reducing the prescribed value of the cumulative lighting time for determining the life span with an increase of the number of times of lighting (see Patent Document 2, for example).
Furthermore, as a conventional discharge lamp ballast apparatus that detects a failure of the discharge lamp, there is one that stores the discharge lamp voltage at fixed time intervals, and detects a failure of the discharge lamp from the variations of the voltage (see Patent Document 3, for example).
Patent Document 1: Japanese Patent Laid-Open No. 2000-82592.
Patent Document 2: Japanese Patent Laid-Open No. 2004-234926.
Patent Document 3: Japanese Patent Laid-Open No. 2004-234924.
However, as for the discharge lamp ballast apparatus described in the Patent Document 1, it stores information only about the types of the faults and the number of occurrences. Accordingly, although it can confirm the fact that the faults occur, it can hardly determine the cause of the fault. In addition, as for the discharge lamp ballast apparatus described in the Patent Document 2, although it can detect the life of the discharge lamp at high accuracy, it can hardly detect a fault due to a cause other than life. Furthermore, as for the discharge lamp ballast apparatus described in the Patent Document 3, although it can detect a malfunction of the discharge lamp, it cannot recognize the process the discharge lamp reaches the malfunction. Therefore the conventional discharge lamp ballast apparatuses have a problem in that it is difficult for them to establish the cause of the fault due to the malfunction of the discharge lamp such as early failures of the discharge lamp and deterioration in lighting characteristics due to change over time.
As typical faults whose causes are hardly determined, there are failures in starting the discharge lamp, and going out and blinking during lighting. These faults can arise because of the life of the discharge lamp, and the malfunction of the discharge lamp (conditions within the discharge lamp alter due to the change over time). As for the former case, it is possible to prevent it before it occurs by estimating the life from the cumulative lighting time or the number of times of lighting as the Patent Document 1. As for the latter case, however, it is difficult to achieve early detection of the malfunction of the discharge lamp. In addition, since the fault can occur in particular conditions, it is difficult to reproduce the fault to examine the phenomenon, and this makes it difficult to identify the cause of the fault. Accordingly, as for the fault due to the malfunction of the discharge lamp, there is a problem of being it necessary to normally store the characteristics at the lighting of the discharge lamp to make a decision as to distinctive characteristics of the discharge lamp.
The present invention is implemented to solve the foregoing problems. Therefore it is an object of the present invention to provide a discharge lamp ballast apparatus capable of facilitating determining the cause of a fault by detecting the distinctive characteristics of the discharge lamp by normally storing information for diagnosing the malfunction of the discharge lamp and by collecting information about the discharge lamp at lighting; capable of recognizing conditions of the discharge lamp at a fault by storing the type of the fault at the fault detection and the contents of operation records at the fault detection as fault information; and capable of checking the conditions of the discharge lamp by referring to the stored contents in a trouble with low reproducibility.